JP2021521017A - Resistor spot welded electrode cap - Google Patents

Abstract

The present invention discloses a resistance spot welded electrode cap. When welding has a dent in the center of the welding contact surface of the electrode cap, the presence of the dent reduces the contact area of the metal workpiece to be welded to the electrode cap of the present invention, and the initial overall heat generation is the welding point. Concentrate on the outer ring of the, slowing heat dissipation, which is advantageous for the nugget to form from the outside to the inside. And, due to the presence of the indentation, the metal workpiece unfolds towards the indentation in the center of the electrode, thereby increasing the weld nugget and reducing spatter and deformation. Therefore, as compared to Jurai's electrode caps, using the electrode caps of the present invention to form weld points of the same size requires lower welding currents, saves power costs and delivers the same currents. Higher weld point strength and stability obtained when used, with fewer weld defects.

Description

The present invention relates to the field of resistance spot welding, and more specifically to welding electrode caps used when performing resistance spot welding between two or more layers of metal workpieces.

With the progress of global warming and energy depletion, the exhaust gas and energy consumption of automobiles are becoming more and more serious, and experiments have shown that when the mass of automobiles is halved, the fuel consumption is also halved. Due to the need for environmental protection and energy saving, weight reduction of automobiles has become a trend of automobile development in the world. Aluminum alloy materials have the advantages of high strength, light weight, excellent corrosion resistance, and are suitable for various molding methods. Therefore, using aluminum alloy instead of steel plate welding can reduce the structural weight by 50% or more, and can reduce the structural weight by 50% or more. Widely used in car bodies.

Currently, the method of connecting body aluminum alloys in automobile manufacturing is mainly the mechanical connection method of riveting. Riveting is a costly, complex process, poor surface quality and a way to increase the weight of the body. An all-aluminum body or hybrid body typically requires 1500 or more rivets. Resistance spot welding uses the workpiece itself and resistance heat to melt the material to achieve connection, and since no filler is required in the connection process, production efficiency is high and automation is easy. Widely used in body manufacturing such as parts such as engine hoods and car doors. In applying aluminum alloys to automobiles, automakers expect to continue to use resistance spot welding to connect aluminum alloys.

However, due to the physical properties of the aluminum alloy itself, there are many problems when welding by a general spot welding process. Due to the high electrical and thermal conductivity of aluminum alloys, spot welding requires particularly large currents and pressures. However, the use of high currents and high electrode pressures requires high manufacturing costs for welding aluminum alloys. In addition, since the molding temperature range of the aluminum alloy is narrow, it causes spatter, internal defects, and welding deformation that are declared during welding. The presence of a high resistance oxide film on the surface accelerates the wear of the weld electrode in the spot welding process, shortens the electrode life, reduces the strength of the weld point, and reduces the surface quality.

Therefore, there is a need for methods for resistance spot welding of aluminum alloys that can achieve higher weld strength, longer electrode life, lower cost, and easier acceleration.

The present invention solves the problems of aluminum alloy resistance spot welding, such as large welding current, serious welding spatter and defects, relatively low welding strength, unstable welding quality, and short electrode life. We propose an electrode cap with a dent in the center of the weld contact surface.

One technical solution adopted by the present invention to solve the above problems is a resistance spot welded electrode cap.
The cylindrical electrode cap body 1 and
A contact surface 3 having a welded surface 31, a circumference 32, and a dent 33, where the dent 33 is located at the center of the contact surface 3, its upper edge is connected to the welded surface 31, and the circumference 32 is the welded surface 31. It is the outer diameter
A transition region from the electrode cap body 1 to the contact surface 3, including a side surface 2 whose shape is an arc surface or a conical surface.
The resistance spot welded electrode cap is provided in which the upper surface and the lower surface of the side surface 2 are connected to the contact surface 3 and the other end of the electrode cap body 1 in the form of an arc surface or a chamfer, respectively.

In another preferred embodiment, the shape of the dent 33 is generally arcuate, or the bottom is flat, the connection with the welded surface 31 transitions at the arc or conical surface, or the center is an arcuate boss. , The connecting portion with the welded surface 31 transitioned at an arc surface or a conical surface.
In another preferred embodiment, the shape of the dent is spherical and its outer diameter is 2 to 15 mm, preferably 2 to 10 mm.
In another preferred embodiment, the dent 33 and the welded surface 31 are connected by an arc or chamfer.
In another preferred embodiment, the side surface 2, the welded surface 31, and the electrode cap body 1 are connected by an arc or chamfer.
In another preferred embodiment, when the side surface 2 is an arc surface, the radius of curvature of the arc surface is equal to or greater than the circumferential radius of the electrode cap body 1.

In another preferred embodiment, when the side surface 2 is a conical surface, the angle of inclination of the conical surface is 0 to 90 °, preferably 10 to 80 °.
In another preferred embodiment, the depth h of the dent 33 is 0.1 to 2 mm, or more preferably 0.1 to 1.2 mm.
In another preferred embodiment, the radius of curvature of the arc surface of the dent 33 is 1 to 50 mm, and when the bottom of the dent is a flat surface, the flat surface is a circle with a radius of 0.1 to 10 mm.
In another preferred embodiment, the welded surface 31 is an annular flat surface, or an annular sphere with the center of the sphere and the electrode cap body on the same side, or an annular sphere with the center of the sphere and the electrode cap body on opposite sides. Or an annular arc surface protruding upwards.
In another preferred embodiment, when the welded surface 31 is an annular flat surface, its outer diameter is in the range of 2 to 30 mm, preferably 6 to 20 mm.
In another preferred embodiment, when the welded surface 31 is an annular spherical surface, the radius of the sphere on which the welded surface 31 is located is 10 to 100 mm.

In another preferred embodiment, when the weld surface 31 is an annular arc surface protruding upwards, the radius of curvature of the arc is 1-10 mm and is perpendicular to the flat surface where the highest and lowest points of the arc surface are located. The distance is 0.1 to 5 mm.
In another preferred embodiment, the resistance spot weld electrode cap further comprises an annular ridge 4 located on the weld surface 31 or dent 33, the cross-sectional shape of the annular ridge being a straight line or a curved line or a combination of straight lines and curves.
In another preferred embodiment, the resistance spot weld electrode cap further comprises a groove 43 formed between two adjacent annular ridges 4.
In another preferred embodiment, the protruding height H of the annular ridge 4 is 20-500 um.
In another preferred embodiment, the number of annular ridges 4 is 0-5.
In another preferred embodiment, the distance between two adjacent annular ridges 4 is 50-2000 um.

Within the scope of the present invention, the above technical features of the present invention and the technical features specifically described below (eg, Examples) may be combined with each other to form a novel or preferred technical solution. Please understand what you can do. Due to space limitations, we will not repeat it here.

The mechanism of the present invention is as follows: Taking the welding of a two-layer metal workpiece as an example, under the action of pressure and current on the weld surface with a central recess, the outside of the two-layer metal workpiece is first. Some areas that are in contact and are affected by the contacted annular electrodes generate resistance heat, forming an annular molten pool, and when the welding time is extended and the central region is loosely contacted, the annular melting is caused by heat conduction. The pond grows towards the center. Since the area of the central region (inside the welding point) of the two metal workpieces corresponding to the dent is small and not in contact with the electrode cap, heat is concentrated on the outside, and when the metal material in the contact region melts and deforms, It presses and expands toward the depression in the center of the electrode, a new contact surface is generated in the center, resistance heat is generated in the new contact surface, and the annular molten pool grows toward the annular center, corresponding to the dent. The contact parts of the two metallic materials form a nugget and the welding is completed.

The presence of dents reduces the initial contact area of the metal workpiece to be welded to the electrode cap of the invention, the overall heat generation is concentrated on the outer ring of the weld point, the heat dissipation is slowed, and the contact area as the weld progresses. Increases and heat dissipates faster, reducing the welding current required to form weld points of the same size, saving power costs and improving electrode life compared to regular electrode caps. Will be done. Since the annular molten pool is formed first, if there is a dent in the center, the annular molten pool grows from the outside to the inside, and the ordinary electrode cap molten pool grows from the inside to the outside. On the contrary, the plasticized metal material is pressed toward the recessed area in the center of the electrode under the action of pressure and current to avoid pores at the end of the weld, spatter, and weld deformation. Helps, thereby increasing the diameter of the nugget and increasing the strength of the weld point.

In the presence of the annular ridge, the annular ridge can penetrate the oxide film on the surface of the aluminum alloy during contact, thereby reducing contact resistance, increasing contact area, increasing heat dissipation, and thereby the electrode welded surface. And by reducing the heat of the contact surface of the aluminum alloy plate, the life of the electrode is improved.

FIG. 1 shows a schematic view of one electrode cap having a dent in the center of the contact surface. FIG. 2 shows one embodiment of a cross-sectional view taken along the line AA of FIG. FIG. 3 shows one embodiment of a cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular flat surface and the dent is a spherical surface. FIG. 4 shows one embodiment of the cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular flat surface, the bottom of the dent is a flat surface, and the welded surface is an arc surface. FIG. 5 shows one embodiment of the cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular flat surface, the center of the dent is an arc-shaped boss, and the connecting portion with the welded surface is transitioned by the arc surface. show. FIG. 6 shows one embodiment of a cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular spherical surface on which the center of the sphere and the electrode cap body are on the same side, and the dent is a spherical surface.

FIG. 7 is a cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular spherical surface on which the center of the sphere and the electrode cap body are on the same side, the bottom of the dent is a flat surface, and the welded surface is an arc surface. An embodiment of the above is shown. FIG. 8 shows an annular spherical surface in which the welding surface is on the same side as the center of the sphere and the electrode cap body, the center of the dent is an arc-shaped boss, and the connecting portion with the welding surface is transitioned by the arc surface. An example of the cross-sectional view of the A cross section is shown. FIG. 9 shows one embodiment of a cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular spherical surface on which the center of the sphere and the electrode cap body are opposite to each other, and the dent is a spherical surface. FIG. 10 is a cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular spherical surface on which the center of the sphere and the electrode cap body are opposite to each other, the bottom of the dent is a flat surface, and the welded surface is an arc surface. An embodiment of the above is shown. FIG. 11 shows an annular spherical surface in which the welding surface is opposite to the center of the sphere and the electrode cap body, the center of the dent is an arc-shaped boss, and the connecting portion with the welding surface is the arc surface. An example of the cross-sectional view of the A cross section is shown.

FIG. 12 shows one embodiment of a cross-sectional view taken along the line AA of FIG. 1 in which the welded surface is an annular arc surface protruding upward and the dent is a spherical surface. FIG. 13 is an embodiment of a cross-sectional view taken along the line AA of FIG. 1, in which the welded surface is an annular arc surface protruding upward, the bottom of the dent is a flat surface, and the welded surface is transitioned to the arc surface. show. FIG. 14 is a cross-sectional view of the AA cross section of FIG. 1 in which the welded surface is an annular arc surface protruding upward, the center of the dent is an arc-shaped boss, and the connecting portion with the welded surface is the arc surface. One embodiment is shown. FIG. 15 shows a schematic view of one electrode cap having a dent in the center of the contact surface and an annular ridge on the welded surface. FIG. 16 shows an enlarged view of the area of the welded surface of the electrode cap of FIG. FIG. 17 shows one embodiment of a partial cross-sectional view of the BB cross section of FIG. FIG. 18 shows another embodiment of a cross-sectional view of the BB cross section of FIG. FIG. 19 shows one embodiment of the cross-sectional shape of an annular ridge, which is a straight line on both sides and an arc tangent to the straight lines on both sides at the top.

FIG. 20 shows one embodiment of a cross-sectional shape of an annular ridge with symmetrical curves on both sides and an arc tangent to the curves on both sides at the top. FIG. 21 shows one embodiment of the cross-sectional shape of an annular ridge that is straight on both the top and both sides. FIG. 22 shows one embodiment of the cross-sectional shape of an annular ridge, which is a straight line on both sides and an arc at the top that intersects the straight lines on both sides. FIG. 23 shows one embodiment of the cross-sectional shape of the annular ridge, which is a curve with different curves on both sides and a curve connected to the curves on both sides at the top. FIG. 24 shows one embodiment of the cross-sectional shape of an annular ridge with symmetrical curves on both sides and a straight line at the top. FIG. 25 shows one embodiment of a cross-sectional shape of an annular ridge that is straight on one side, curved on the other, and curved or straight at the top.

FIG. 26 shows one embodiment of the cross-sectional shape of an annular ridge whose entire cross-section is arcuate. FIG. 27 shows one embodiment of a cross-sectional view taken along the line BB of FIG. 15 in which the annular ridge is located on the welded surface when the welded surface 31 is an annular flat surface and the dent 33 is a spherical surface. FIG. 28 shows one embodiment of a cross-sectional view taken along the line BB of FIG. 15 in which the annular ridge is located on both the welded surface and the dent when the welded surface is an annular flat surface and the dent is a spherical surface. FIG. 29 is a cross-sectional view of the BB cross section of FIG. 15 in which the annular ridge is located on the welded surface when the welded surface is an annular flat surface, the dent bottom is a flat surface, and the transition from the welded surface to the arc surface. One embodiment is shown.

In FIG. 30, when the welded surface is an annular flat surface, the center of the dent is an arc-shaped boss, and the connecting portion with the welded surface transitions at the arc surface, the annular ridge is located on the welded surface BB of FIG. An example of a cross-sectional view of a cross section is shown. FIG. 31 is a cross-sectional view of the BB cross section of FIG. 15 in which the annular ridge is located on the welded surface when the welded surface is an annular spherical surface on which the center of the sphere and the electrode cap body are on the same side and the dent is a spherical surface. One embodiment is shown. FIG. 32 shows an annular sphere in which the welding surface is on the same side as the center of the sphere and the electrode cap body, the bottom of the dent is a flat surface, and the annular ridge is located on the welding surface when transitioning from the welding surface to the arc surface. An example of the cross-sectional view of the BB cross section of FIG. 15 is shown.

FIG. 33 shows an annular sphere in which the welding surface is on the same side as the center of the sphere and the electrode cap body, the center of the dent is an arc-shaped boss, and when the connecting portion with the welding surface transitions on the arc surface, the annular ridge is formed. An example of a cross-sectional view of the BB cross section of FIG. 15 located on the welded surface is shown. FIG. 34 is one of the cross-sectional views of the BB cross section of FIG. 15 in which the welded surface is an annular arc surface protruding upward and the annular ridge is located on both the welded surface and the dent when the dent is spherical. An example is shown. FIG. 35 shows an annular arc surface with the welded surface protruding upward, a flat surface at the bottom of the dent, and an annular ridge located on both the welded surface and the dent when transitioning from the welded surface to the arc surface. An example of the cross-sectional view of the BB cross section of the above is shown. FIG. 36 shows an overall side view when welding by metal workpiece resistance spot welding.

FIG. 37 shows a schematic cross-sectional view of one initial stage of welding when welding is performed using the present invention when the annular ridge is not installed on the welding surface of the electrode cap of the present invention. FIG. 38 shows a schematic cross-sectional view of one initial stage of welding when an annular ridge is installed on the welded surface of the electrode cap of the present invention and welded using the present invention. FIG. 39 shows the cross-sectional shape of the weld point after resistance spot welding to two 2 mm 5182-O aluminum alloys using an ordinary electrode cap. FIG. 40 shows the cross-sectional shape of the weld point after resistance spot welding to two 2 mm 5182-O aluminum alloys using the electrode cap of Example 1 of the present invention.

1-electrode cap body, 11-electrode mounting channel, 12-electrode cap body circumference, 2-side surface, 3-contact surface, 31-welded surface, 32-circumference, 4-annular ridge, 41-Example 2. One annular ridge, another annular ridge of 42-Example 2, 43-groove, 44-annular ridge cross section, 45-annular ridge 41 side surface, 46-annular ridge 42 side surface, 5 -Welding gun, 51-1st welding gun arm, 52-2nd welding gun arm, 53-1st welding electrode cap, 54-2nd welding electrode cap, 6,7-welding workpiece, 8-welding work Pieces 6 and 7 Welded Nugget Zones, 9-Nuggets, -Diameter of Circumference 12; Diameter of Circumference 32,-Outer Diameter Size When Indentation is Spherical, -Distance between Two Adjacent Ring Rises, -Width of the annular ridge, h-Depth depth, H-Height of the annular ridge protrusion.

As a result of extensive scrutiny, we have found through numerous experiments that large welding currents are required for resistance spot welding of aluminum alloys, welding spatter is severe, welding strength is relatively low, and electrode life is long. An electrode cap having a dent in the center of the contact surface, which can solve problems such as shortness, was discovered, and the present invention was completed based on this.
The present invention will be further described below with specific examples. It should be understood that these examples are used only to illustrate the invention and do not limit the scope of the invention. Further, since the drawings are schematic drawings, the apparatus and equipment of the present invention are not limited by the size or ratio of the schematic drawings.

In the claims and specification of this patent, related terms such as first and second are used only to distinguish one entity or operation from another, and that between those entities or operations. Note that it does not necessarily require such an actual relationship or order. It should be noted that the term "contains", "inclusion" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a set of elements may be a process, method, article, or device. Not only those elements, but also other elements that are not explicitly listed, or elements that are specific to this process, method, article, or device. Without further restrictions, an element defined by the phrase "contains one" does not preclude the presence of the same other element within the process, method, article, or device that contains the element.

Example 1
As shown in FIGS. 1 and 2, the resistance spot welded electrode cap of this embodiment includes an electrode cap body 1 having a substantially cylindrical shape, and a contact surface 3 between the electrode and the weld metal material. An electrode mounting channel 11 is provided at one end of the main body 1, and a circumference 12 is provided at the other end. The contact surface 3 includes a welded surface 31, a circumference 32, and a dent 33. The dent 33 is located in the central region of the contact surface 3. The electrode cap further includes a side surface 2, the side surface 2 is a transition region in which the circumference 12 of the main body 1 transitions to the circumference 32 of the contact surface 3, the shape of the side surface 2 is an arc surface, and the side surface 2 is a cone. Note that it may be. When the side surface 2 is an arc surface, the radius of curvature of the arc surface is equal to or greater than the circumferential radius of the electrode cap body 1, and when the side surface 2 is a conical surface, the inclination angle of the conical surface is 0 to 90 °, which is preferable. Is 10 to 80 °. The upper surface of the side surface 2 is a portion that comes into contact with the dent, and the lower surface is a portion that comes into contact with the main body 1. It should be explained that when the diameter of the circumference 12 and the diameter of the circumference 32 are the same, the side surface 2 becomes a part of the electrode cap main body 1. What should be described here is that the diameter of the circumference 12 is the diameter of the electrode cap body 1, and the radius of the circumference 12 is the radius of the electrode cap body 1. The side surface 2 can also have other suitable shapes.

One end of the main body 1 refers to one end connected to the resistance spot welder during resistance spot welding, and the other end refers to one end close to the welding workpiece contact surface.
In another preferred embodiment, the shape of the electrode mounting channel 11 can be truncated conical or cylindrical, and the shape of the electrode mounting channel 11 can be, or any other suitable shape.

The circumference 32 and the circumference 12 are parallel, and the circumference 32 is a circumference whose diameter size has changed after the circumference 12 has moved upward along the axis perpendicular to the main body 1. It can be understood that the connecting line between the center of the circle 32 and the center of the circumference 12 coincides with the axis of the main body 1, and the diameter of the circumference 32 is equal to or less than the diameter of the circumference 12.

The dent 33 can be understood as a hole of a specific shape dug in the center of the contact surface 3, and the shape of the dent 33 is an arc surface or a flat surface in the center and contacts with the annular weld surface 31. The portion is an arc surface, or the center is an arc-shaped boss, and the contact portion with the welded surface 31 is an arc surface. The depth of the dent 33 is 0.1 to 2 mm, preferably 0.1 to 1.2 mm. The depth of the dent 33 here is the vertical distance from the flat surface where the edge where the upper portion of the dent 33 contacts the welding surface 31 is located to the flat surface where the bottom of the dent 33 is located.

In another preferred embodiment, when the shape of the dent 33 is spherical and the shape of the dent 33 is spherical, its outer diameter is 2 to 15 mm, preferably 4 to 12 mm.
The welded surface 31 is an annular flat surface, or an annular spherical surface in which the center of the sphere and the electrode cap body are on the same side, or an annular spherical surface in which the center of the sphere and the electrode cap are on opposite sides, or project upward. It is an annular arc surface.
When the center of the sphere and the electrode cap body are on the same side and the center of the sphere and the electrode cap body are on opposite sides, the welding surface 31 is the critical surface, and the direction in which the center of the sphere approaches the electrode cap body 1 is the electrode cap. The direction on the same side of the main body, and the direction in which the center of the sphere is separated from the electrode cap main body 1, indicates the direction on the opposite side of the electrode cap main body.

When the welded surface 31 is an annular flat surface, its outer diameter range, that is, the diameter of the circumference 32 is 2 to 30 mm, preferably 5 to 20 mm, and when the welded surface 31 is an annular spherical surface, the welded surface 31 The radius of the sphere in which is located is 10 to 100 mm, and when the welded surface 31 is an annular arc surface protruding upward, the radius of curvature of the arc is 1 to 10 mm, and the highest and lowest points of the arc surface are located. The vertical distance of the flat surface is 0.1 to 5 mm.

3 to 14 show each embodiment of the cross-sectional view taken along the line AA of FIG. 1 when the shapes of the welded surface 31 and the dent 33 are combined. The cross-sectional view of the AA cross section of FIG. 1 may be any combination of the following. For example, the welded surface is an annular flat surface, the dent is a spherical surface (Fig. 3) or the welded surface is an annular flat surface, the bottom of the dent is a flat surface, and the welded surface is an arc surface (Fig. 4) or the welded surface. Is an annular flat surface, the center of the dent is an arc-shaped boss, and the connection part with the welded surface is an arced surface (Fig. 5) or the welded surface is an annular spherical surface where the center of the sphere and the electrode cap body are on the same side. Yes, the dent is a sphere (Fig. 6) or the welded surface is an annular sphere with the center of the sphere and the electrode cap body on the same side, the bottom of the dent is a flat surface, and the welded surface is an arc surface (Fig. 7) or The welded surface is an annular sphere with the center of the sphere and the electrode cap body on the same side, the center of the dent is an arc-shaped boss, and the connecting part with the welded surface transitions to the arced surface (Fig. 8) or the welded surface is a sphere. An annular sphere with the center and electrode cap body on opposite sides, a dent is a sphere (Fig. 9) or a welded surface is an annular sphere with the center of the sphere and the electrode cap body on opposite sides, and the bottom of the dent is a flat surface. The welded surface is an arc surface (Fig. 10) or the welded surface is an annular sphere with the center of the sphere and the electrode cap body on the opposite side, the center of the dent is an arc-shaped boss, and the connecting part with the welded surface is the arc surface. The transition (FIG. 11) or welded surface is an upwardly projecting annular arc, the dent is a spherical surface (FIG. 12) or the welded surface is an upwardly projecting annular arc, and the bottom of the dent is a flat surface. The welded surface is a transition at the arc surface (Fig. 13) or the welded surface is an annular arc surface protruding upward, the center of the dent is an arc-shaped boss, and the connecting part with the welded surface is transitioned at the arc surface (Fig. 14). ) Can be the shape.

It should be noted that the electrode caps of the present invention can be made of any conductive and thermally conductive material, for example copper chromium (CuCr) alloy, copper chromium zirconium (CuCrZr) alloy, copper containing alumina particles. Can be made of copper alloys, including copper alloys, various other copper alloys that can be used as electrode materials, said aluminum alloys, including deformed aluminum alloys or cast aluminum alloys, aluminum-magnesium alloys, aluminum-silicon alloys, aluminum-magnesium. Includes aluminum alloy substrates with coated or uncoated surfaces such as aluminum alloys such as-silicon alloys, aluminum-zinc alloys, and aluminum-copper alloys. In addition, the material state includes various tempering such as annealing, strain strengthening, and solid-liquid strengthening. The thickness of the aluminum substrate is generally between 0.3 mm and 6.0 mm, preferably between 0.5 mm and 3.0 mm.

Example 2
The resistance spot weld electrode cap of this example is similar to that of Example 1, except that the welded surface 31 or dent 33 of this example has a protruding annular ridge 4 as shown in FIGS. 15-16. A groove 43 is formed between two adjacent annular ridges. The annular ridge 4 can be understood as an annular structure formed by rotating a flat surface having a specific shape as the cross section 44 once around the central axis of the electrode cap, and here, the lower portion of the cross section 44 is welded. In contact with the surface 31, the entire cross section 44 is perpendicular to the welded surface 31. The central axis of the electrode cap is a straight line that passes through the center of the circumference 12 and is perpendicular to the circumference 12. It should be noted that the number of said annular ridges is not limited to two and may be one or more as needed.

As shown in FIGS. 17 to 18, the protruding annular ridge 4 has two projecting methods as shown in FIGS. 17 and 18 on the welded surface 31, and the projected annular ridge 4 is projected with respect to the welded surface 31. The height H can be 20-500 um. The protruding height here refers to the vertical distance H from the lower part to the uppermost part of the annular ridge 4 in the direction perpendicular to the welded surface 31 or the dent surface. The width of the groove 43 formed by the spacing between the two adjacent annular ridges, i.e. the distance between the two annular ridges, is 50-3000 um. The width of the groove 43 between two adjacent annular ridges here is defined as the width of the two adjacent annular ridges 41 and 42, as shown in FIG. 17 in a partial cross-sectional view of the electrode cap having the annular ridge. It is the distance between the two points 45 and 4 points 6 located respectively, and the points 45 and 46 are located on two adjacent side surfaces of the annular ridge 41 and the annular ridge 42, and the connecting line between the two points. Is parallel to the welded surface 31. The width of the annular ridge can be 200-3000 μm, or more preferably 500-2000 μm. The width of the annular ridge here refers to the distance between two points on two sides of the same annular ridge, the two points located on the same cross section of the annular ridge. It should be explained that when the number of annular ridges is 3 or more, the groove width between two adjacent annular ridges may be the same or different, and the width of each annular ridge is the same. May also be different.

As shown in FIGS. 19-26, the possible shapes and structures of the annular ridge cross section 44 (a represents the bottom of the cross section, b represents the top of the cross section, c represents both sides of the cross section) are shown. The shape of the cross section 44 can be of the following structure: a straight line on both sides and an arc tangent to the straight line on both sides (Fig. 19) or a symmetric curve on both sides and an arc tangent on the curved line on both sides (Fig. 19). FIG. 20) or both the top and both sides are straight lines (FIG. 21) or both sides are straight, the top is an arc that intersects the two-sided straight line (Fig. 22) or both sides are different curves, and the top is connected to the two-sided curve. Curved (FIG. 23) or symmetric on both sides, top is straight (FIG. 24) or straight on one side, other is curved, top is curved or straight (FIG. 25) or overall cross section The shape is semi-circular (Fig. 26). It should be noted that the cross-sectional structure of the annular ridge described above is only a few preferred structures, and other structures suitable for the cross-sectional shape of the annular ridge can also be used.

As shown in FIGS. 27 to 35, when the shapes of the welded surface 31 and the dent 33 are different, the situation where the annular ridge is located on the welded surface 31 and the dent 33 is shown. Only some preferred positions on the weld surface and dents are shown, and the annular ridge can be located on the weld surface 31 only, or only the dent 33, or both the weld surface 31 and the dent 33, the weld surface 31 and the dent 33. The number of annular ridges located in can be randomly selected according to usage.

Example 3
The present embodiment discloses an apparatus and process of the electrode cap welded aluminum alloy work piece of the present invention, and as shown in FIG. 36, 5 is a first aluminum alloy work piece 6 and a second aluminum alloy work piece 7. It is a welding gun at a welding position 8 that can be used for resistance spot welding for connecting, and the welding gun 5 is a first welding gun arm 51, a second welding gun arm 52, a first welding electrode cap 53, and a second welding. Includes electrode cap 54. The first aluminum alloy work piece 6 and the second aluminum alloy work piece 7 are composed of an aluminum alloy such as an aluminum-magnesium alloy, an aluminum-silicon alloy, an aluminum-magnesium-silicon alloy, or an aluminum-copper alloy, and are made of aluminum. The thickness of the alloy workpiece is 0.5 to 3 mm. More preferably, the aluminum alloy workpiece can be a 2.02-O aluminum alloy with a thickness of 2.0 mm. At the time of welding, the aluminum alloy workpieces may be two (eg, only 6 and 7) or a combination of two or more, and the thickness of each aluminum alloy workpiece may be the same or different. You may. It should be explained that the term "workpiece" as used herein refers to metal sheet layers, protrusions, castings and other aluminum alloy parts or steel and magnesium alloy workpieces that can be spot welded. That is. Welding gun arms 51, 52 are usually part of a larger automatic welding operation, generally including C-type, X-type, and other types of structural shapes, and are usually well-understood robotic or automatic in the art. Realized by components.

The first welding gun arm 51 and the second welding gun arm 52 are provided with a first welding electrode cap 53 and a second welding electrode cap 54 attached as described in Examples 1 and 2. There is. The welding gun arm is operated so that the electrode caps 53 and 54 are precisely attached to the workpieces 6 and 7 during spot welding, and conducts a force and an electric current through the welding gun arm and the electrode cap to conduct the work pieces 6 and 7. The abutting portion 8 of the is melted so that a spot welded joint is formed. The two electrode caps 53, 54 may have the various structures described in Examples 1 and 2, and the structures of 53 and 54 may be the same or different.

FIG. 37 shows a schematic cross-sectional view of one initial stage of welding when welding is performed using the electrode cap of the first embodiment of the present invention. The electrodes 53 and 54 have the same structural size, and the welding gun conducts pressure and current through the welding surface 31 during welding, and the region where the contact portions of the two layers of metal materials 6 and 7 are subjected to the annular electrode action is It generates resistance heat, which forms the nugget 9 and then the annular molten pool. The area where the outside of the two-layer metal workpiece first contacts and the contact area is subjected to the annular electrode action generates resistance heat, which forms an annular molten pool, due to the extension of the welding time and the gentle contact of the central region. The annular molten pool grows toward the center due to the action of heat conduction, and the area of the central region (inside the welding point) of the two metal workpieces corresponding to the dents is relatively small and does not contact the electrode cap. Therefore, the heat is concentrated on the outside, and due to the melting and plastic deformation of the metal material in the contact area, it is pushed toward the recess in the center of the electrode and expanded, then a new contact surface is generated in the center, and resistance heat is generated on the new contact surface. Generates and forms a ring, the molten pool grows toward the center of the ring, resistance heat is generated at the new contact surface, the annular molten pool grows toward the center of the ring, and then two corresponding dents. Welding was completed by allowing the contact parts of the metal material to form a nugget. Due to the presence of dents, the electrode cap of the present invention has a reduced initial contact area with the metal workpiece, concentrated overall heat generation, slowed heat dissipation, and increased contact area as welding progressed, resulting in heat dissipation. It will be faster. Therefore, compared to ordinary electrode caps, the welding current required to form weld points of the same size is reduced, power costs are saved, and electrode life is extended. Since the annular molten pool is formed first, if there is a dent in the center, the annular molten pool grows from the outside to the inside, and the ordinary electrode cap molten pool grows from the inside to the outside. On the contrary, the plastic metal material is compressed toward the recessed area in the center of the electrode under the action of pressure and current, which helps to avoid pores, spatter, and welding deformation at the edge of the weld point. Increases the diameter of the nugget and improves the strength of the weld point.

In the presence of annular ridges, upon contact, the annular ridges can penetrate the oxide film on the surface of the piercing aluminum alloy, thereby reducing contact resistance, increasing contact area and increasing heat dissipation, thereby increasing heat dissipation. The life of the electrode is improved by reducing the heat of the contact surface between the electrode welded surface and the aluminum alloy plate.
FIG. 38 shows a schematic cross-sectional view of one initial stage of welding when welding is performed using the electrode cap of the second embodiment of the present invention. The welding principle is similar to the welding principle of FIG. 37.

Example 4
FIG. 39 shows the cross-sectional shape of the weld point after resistance spot welding to two 2 mm Sasa 5182-O aluminum alloys using an ordinary electrode cap. As can be seen from the figure, the nugget diameter is only 6.08 mm, there are obvious shrinkage defects inside, spatter is severe, and edge weld deformation is large, resulting in a decrease in weld point strength.

Example 5
FIG. 40 shows 2 after resistance spot welding to two 2 mm thick 5182-O aluminum alloys using the electrode cap of Example 1 of the present invention and adopting the welding apparatus and welding principle of Example 3. The cross-sectional shape of one aluminum alloy welding point is shown. As can be seen from the figure, the nugget diameter reaches 8.23 mm, there are no obvious weld defects inside, no spatter, no obvious deformation at the edges of the weld point, which increases the strength of the weld point. Greatly improved.

The present invention has been disclosed as described above in preferred embodiments, but is not intended to limit the invention. One of ordinary skill in the art can make various equivalent modifications or substitutions without departing from the spirit and scope of the invention, all within the scope of the invention. Therefore, the scope of protection of the present invention shall be in accordance with the scope defined by the claims of the attachment of this application.

Claims (10)

Resistor spot welded electrode cap
The cylindrical electrode cap body (1) and
A contact surface (3) having a welded surface (31), a circumference (32), and a dent (33), where the dent (33) is located in the center of the contact surface (3) and is the upper edge of the dent (33). Is connected to the welded surface (31), and the circumference (32) is the outer diameter of the welded surface (31).
It is a transition region from the electrode cap body (1) to the contact surface (3), and includes a side surface (2) whose shape is an arc surface or a conical surface.
The resistance spot welding is characterized in that the upper surface and the lower surface of the side surface (2) are connected to one end of the contact surface (3) and the electrode cap body (1), respectively, in the form of an arc surface or a chamfer. Electrode cap. The shape of the dent (33) is an arc surface as a whole, or the bottom is a flat surface, the connection part with the weld surface (31) transitions with an arc surface or a conical surface, or the center is an arc-shaped boss, and the weld surface. The resistance spot welded electrode cap according to claim 1, wherein the connecting portion with (31) is transitioned at an arc surface or a conical surface. The resistance spot welded electrode cap according to claim 1 or 3, wherein the depth h of the dent (33) is 0.1 to 2 mm. When the dent (33) is an arc surface as a whole, the radius of curvature of the dent (33) arc surface is 1 to 50 mm, and when the bottom of the dent is a flat surface, the flat surface is a circle with a radius of 0.1 to 10 mm. The resistance spot welded electrode cap according to claim 1 or 3, wherein the resistance spot welded electrode cap is characterized by the above. The welded surface (31) is an annular flat surface, or an annular sphere with the center of the sphere and the electrode cap body on the same side, or an annular sphere with the center of the sphere and the electrode cap body on opposite sides, or upwards. The resistance spot welded electrode cap according to claim 1, wherein the annular arc surface is projected on the surface. Claimed, further comprising an annular ridge (4) located on a welded surface (31) or a dent (33), wherein the cross-sectional shape of the annular ridge (4) is a straight line or a curved line or a combination of straight lines and curves. Item 2. The resistance spot weld electrode cap according to Item 1. The resistance spot weld electrode cap according to claim 1, further comprising a groove (43) formed between two adjacent annular ridges (4). The resistance spot welded electrode cap according to claim 7, wherein the protrusion height H of the annular ridge (4) is 20 to 500 μm. The resistance spot weld electrode cap according to claim 7, wherein the number of annular ridges (4) is 0-5. The resistance spot welded electrode cap according to claim 7, wherein the distance between two adjacent annular ridges (4) is 50 to 3000 um.

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